Symbolism, Imagery, Allegory
The oilcloth square is the comrade's "ticket" on his journey. Some ticket, right? But it totally works. The kid has no money, but his handy little fabric swatch pays his way, helping him obtain food and shelter. It also serves as a form of identification. With a message from Communist HQ saying that the comrade suffered badly in Budapest, and requesting that comrades help him along his way, the square of oilcloth is basically a way for the young man to vouch for his identity in foreign lands, as well as tap into a network of support.
In other words, the square of oilcloth is part identification card, part political party membership card, part message from the head honchos, and part ticket for free food. On a more subtle level, though, the cloth is a reminder of just how alone this young man is in the world. He has very little to get by on but the square of oilcloth, and he's dependent on the kindness of strangers—otherwise there'd be no need for the note eliciting assistance for him. So is it a hook-up of sorts? Absolutely. But it's also only necessary because the comrade is so stinking alone.